When I had to replace the rear cap on my 1999 Tradewinds I found the factory had reinforced the cap with 3/4" exterior plywood where the ladder attached, so I glued in some on the new cap. These pieces were all the way across left to right on the ladder side and about 18” top to bottom. I would guess Country Coach did something similar to the Allure. So somewhere close to the original ladder attachments should hit them.
I installed my new ladder with #10 self tapping stainless steel sheet metal screws long enough to go through the plywood, and after a year and a half it's still tight and sturdy. My ladder had four of these screws for each standoff so there is plenty of strength there.
In the top where the ladder fastens to the roof I used #10 Jack nuts because the roof was pretty thin and I couldn't get to it to add the plywood. Again there were four on each side.
1999 Tradewinds 7372 Cat 3126